两种Catalan C++的实现

I.

代码如下

#include <iostream>long int h(long int n){if (n > 1){long int re = 0;for (int i = 1; i <= n; ++i)re += h(i - 1) * h(n - i);return re;}elsereturn 1;}int main(){long int a;std::cin >> a;std::cout << h(a);return 0;}

II.

代码如下:

#include <iostream>long int h(long int n){if (n > 1){long int re = 0;re = 2 * (2 * n - 1) / (n + 1) * h(n - 1);return re;}elsereturn 1;}int main(){long int a;std::cin >> a;std::cout << h(a);return 0;}